"Knowing he was dying, Arthur asked Percival to take Excalibur back to the Lady of the Lake. However Percival decided to keep Excalibur for himself and on returning to Arthur reporting that nothing had happened. Arthur told Percival that he had not done what was asked and to do it. This time Percival did throw Excalibur into the lake and the Lady caught it. Soon after Arthur died and his body was taken to the Isle of Avalon where, according to legend, he waits until England needs him again.
The story doesn't end there. Galahad took the throne as Arthur's chosen and at least stemmed the disintegration of Arthur's kingdom. Percival continued his grail quest eventually finding it but when he touched it he disappeared.